The synthesis of 1,3-Dialkly-2-arlybenzimidazolium salts by using microwave and classical heating methods and investigation of their properties

Ionic liquids which composed entirely of ions are used as catalyst and reaction medium (solvent) commonly in recent years. Benzimidazolium salts include biologically active benzimidazole ring and are the structural analogue of ionic liquids. The irusage as corrosion inhibiting additive and especially as carbene precursor for catalytic purposes are also very common. Dueto the importance of the benzimidazole nucleus, it is important to design and synthesize novel benzimidazolium salts. In this study, a series of new 1,3-Dialkyl-2-arylbenzimidazolium salts ((arbim)X) will synthesize by N-alkylation of 1-Methly-2-arylbenzimidazoles by using microwave or classical heating methods. The synthesis were performed in a multimode microwave reactor, under mild conditions (120 W) and by using a small amounts of solvent (DMF). Structures of the synthesized compounds were idendified by using IR, 1H-NMR and 13C-NMR techniques. The reactions conducted under microwave conditions were achived the higher yields in shorter times than classical heating.. Considering the reactions repeated by classical heating, it was determined that the reaction times were decreased 3-6 hours to 5-35 minutes with microwave. The reaction rates are increased by 5-72 times with microwave compared to conventional heating. Inaddition, yields have increased from 4-81 % to 64-96 % value. The method is advantageous regarding simplicity, the usage of mild conditions (120 W microwave irradiation) and small amounts of solvent, easy purification and achieving high yields in short times. The results of this study is very important in the areas of synthetic organic chemistry, microbiology, pharmaceutical chemistry and chemical catalysis. Keywords: Benzimidazolium salts; benzimidazole; synthesis; microwave; ionic liquids